SLLSEM3G November 2014 – March 2017 ISO7841
PRODUCTION DATA.
Refer to the PDF data sheet for device specific package drawings
The ISO7841 device uses an ON-OFF keying (OOK) modulation scheme to transmit the digital data across a silicon-dioxide based isolation barrier. The transmitter sends a high-frequency carrier across the barrier to represent one digital state and sends no signal to represent the other digital state. The receiver demodulates the signal after advanced signal conditioning and produces the output through a buffer stage. If the EN pin is low then the output goes to high impedance. The ISO7841 device also incorporates advanced circuit techniques to maximize the CMTI performance and minimize the radiated emissions because of the high-frequency carrier and IO buffer switching. The conceptual block diagram of a digital capacitive isolator, Figure 15, shows a functional block diagram of a typical channel.
Figure 16 shows a conceptual detail of how the ON-OFF keying scheme works.
Table 1 lists the device features.
PART NUMBER | CHANNEL DIRECTION | RATED ISOLATION | MAXIMUM DATA RATE | DEFAULT OUTPUT |
---|---|---|---|---|
ISO7841 | 3 Forward, |
5700 VRMS / 8000 VPK (1) | 100 Mbps | High |
1 Reverse | ||||
ISO7841F | 3 Forward, |
5700 VRMS / 8000 VPK (1) | 100 Mbps | Low |
1 Reverse |
Many applications in harsh industrial environment are sensitive to disturbances such as electrostatic discharge (ESD), electrical fast transient (EFT), surge, and electromagnetic emissions. These electromagnetic disturbances are regulated by international standards such as IEC 61000-4-x and CISPR 22. Although system-level performance and reliability depends, to a large extent, on the application board design and layout, the ISO7841 device incorporates many chip-level design improvements for overall system robustness. Some of these improvements include
Table 2 lists the ISO7841 functional modes.
VCCI | VCCO | INPUT (INx)(3) |
OUTPUT ENABLE (ENx) |
OUTPUT (OUTx) |
COMMENTS |
---|---|---|---|---|---|
PU | PU | H | H or open | H | Normal Operation: A channel output assumes the logic state of its input. |
L | H or open | L | |||
Open | H or open | Default | Default mode: When INx is open, the corresponding channel output goes to its default logic state. Default= High for ISO7841 and Low for ISO7841F. | ||
X | PU | X | L | Z | A low value of Output Enable causes the outputs to be high-impedance |
PD | PU | X | H or open | Default | Default mode: When VCCI is unpowered, a channel output assumes the logic state based on the selected default option. Default= High for IISO7841 and Low for ISO7841F. When VCCI transitions from unpowered to powered-up, a channel output assumes the logic state of its input. When VCCI transitions from powered-up to unpowered, channel output assumes the selected default state. |
X | PD | X | X | Undetermined | When VCCO is unpowered, a channel output is undetermined (2). When VCCO transitions from unpowered to powered-up, a channel output assumes the logic state of its input |